1. Field of the Invention
The present invention relates to a semiconductor fabricating apparatus and a method therefor. More particularly, the present invention relates to an apparatus and method for inspecting whether wafers are loaded normally in a carrier when the carrier is supplied to an indexer for another fabrication apparatus.
2. Description of the Related Art
It is known that many wafer processes, including several cleaning processes, are conducted during the fabrication of semiconductor devices. Typically a predetermined number of wafers are loaded into a carrier where the wafers are held in place by a pair of slots along opposite sides of the carrier. During one process, the wafer carrier is provided to an indexer which in turns feeds wafers individually in sequence to the next wafer processing apparatus, for example, a wafer cleaning apparatus such as a spin scrubber. The indexer counts the number of wafers loaded in the carrier; and an indexer arm automatically transfers the wafers from the carrier to the wafer processing apparatus one at a time, in sequence, as controlled by a start signal.
However, a problem occurs if any wafer is improperly positioned in the slots inside the carrier. For example, a wafer may be slanted or inclined, i.e., it may have one side of the wafer in one slot of a pair along one side of the carrier and have the other side of the wafer in a slot of a different pair along the other side of the carrier. If the defectively loaded wafers are handled by an indexer for the following apparatus, such as a spin scrubber, the wafers or parts of the next apparatus may be damaged. Then the operation of the processing equipment has to be stopped and productivity at the fabrication facility is decreased.